//简单栅格布局系统
.row:before,
.row:after {
  content: "";
  display: table;
  clear: both;
}
.generate-columns(24);

.generate-columns(@n, @i: 1) when (@i =< @n) {
  .col-@{i} {
    width: (@i * 100% / @n);
  }
  .generate-columns(@n, (@i + 1));
}
